Vehicle seat

ABSTRACT

The present invention relates to a vehicle seat, which can normally move between a lower end position and an upper end position. The seat comprises a bellows for cushioning/dampening movements of the seat in a vertical direction and also a belt reel which together with a belt is capable of locking the position of the seat at an optional height between the end positions.

TECHNICAL FIELD

The present invention relates to a vehicle seat with a seat which cannormally move between a lower end position and an upper end position andfirst means capable of cushioning/dampening movements of the seat in avertical direction.

BACKGROUND TO THE INVENTION

Driver comfort and ergonomics are areas in which a lot of work andimprovements have been made, and especially driver comfort for vehiclesin commercial traffic, such as long-distance lorries and buses. Sincethe vehicle is the driver's workplace, where he spends several hours, itis necessary for comfort and thus the working environment to be assatisfactory as possible. A lot of work has therefore been put into thevehicle suspension on the one hand and the suspension of driver's cabson the other. Furthermore, driver's seats have been improved as regardspossibilities for adjustment to achieve the optimum sitting position andsuspension.

However, it has proved to be the case that the suspension of the seat isdisadvantageous in certain situations. In the event of heavy braking orcollisions, the driver and the seat are exposed to forces directedforwards/upwards, which are amplified by the suspension and heightadjustment devices of the seat. Moreover, in certain situations and forcertain road conditions the various suspension systems in the vehiclecan come to act in opposition, so that the seat suspension systemamplifies irregularities instead of dampening these.

DESCRIPTION OF THE INVENTION

The object of the present invention is to provide a device capable oflocking the seat at the desired height and blocking the seat's movementswhen it is exposed to strong acceleration upwards.

This is achieved according to an aspect of the invention by a device fora vehicle seat of the type specified in the introduction, characterisedin that the seat comprises means capable of locking the position of theseat cushion at an optional height between said end positions.

According to an aspect of the invention, a seat is provided which alsocomprises means capable of locking the seat's movement upwards when itis exposed to acceleration in this direction.

These and other aspects and advantages of the present invention willbecome clear from a detailed description of a preferred embodiment ofthe invention and the following patent claims.

BRIEF DESCRIPTION OF DRAWINGS

In the following description of a preferred embodiment, reference willbe made to the attached drawings, of which

FIG. 1 shows a side view of a vehicle seat in a top end positionaccording to an embodiment of the invention, and

FIG. 2 shows a view from behind of the vehicle seat of FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT

The drawings show a preferred embodiment of the present invention. Itconsists of a vehicle seat 1 which comprises a seat 10 arranged on anunderbody generally designated by the number 12. The underbody comprisestwo lower rails 14 affixed to the floor in the vehicle. Arrangeddisplaceably in relation to the lower rails 14 are two upper rails 16,which grip around the lower rails 14 so that they are fixed to oneanother vertically. The rails 14, 16 are further arranged with a lockingdevice (not shown) for locking in relation to each other in an optionalposition. The locking device is activated by a handle 18. Firmlyattached to the upper rails 16 is a frame 20, to which frame ascissor-type lifting system 22 is attached. The lower front arms 24 ofthe scissor-type lifters are affixed pivotably to the frame 20 and thelower rear arms 26 to an articulated arm 28, the other end of thearticulated arm being arranged pivotably to the frame. The upper frontarms 30 are affixed to a frame 32 in the seat 10 and the upper rear arms34 are arranged pivotably to the seat frame 32 via an articulated arm36. This scissor-type system allows parallel movement of the seat 10vertically in relation to the floor.

Arranged between the seat 10 and the frame 20 in their front sections isan air spring 40 in the form of a bellows. The bellows 40 is connectedto a pneumatic system (not shown) capable of pressurizing the bellowsvia a valve which is preferably controlled 42 from the driver'sposition. By means of the valve the driver can set whether he will admitmore air to the bellows 40 or let air out, whereupon the height of thevehicle seat is changed. Disposed between the seat 10 and the frame 20in their back sections is a locking device 50. In the embodiment shown,it comprises a belt reel 52 affixed to the frame 20 and a belt 54, whichis partly rolled up on the reel 52. The belt reel 52 is arranged in therear part of the underbody 12, i.e. in the part which is opposite thebellows 40 arranged in the front part of the underbody. More precisely,it is arranged on the rear part of the frame 20 midway between the rails14/16. The other, free, i.e. not rolled-up end 55 of the belt 54 isfastened to the seat 10; in the embodiment shown fastened to a cross-bar56 between the articulated arms 36. The cross-bar 56 is provided forthis purpose with a belt fastening device 57. The belt reel 52 is of thetype used for inertia-reel seat belts, i.e. it is disposed with springelements, which strive constantly to reel the belt into the reel, at thesame time as the belt can be pulled out at an even extraction speed.However, if the belt should be pulled out suddenly, a locking functionsets in and locks the reel. The belt reel 52 is also arranged accordingto the invention with a locking mechanism which comes into force onactivation, such as an electric impulse for example which locks the reelvia an electromagnet.

The device according to the invention is conceived to function asfollows. When the driver or passenger gets into the vehicle to drive orride, he sets a suitable driving height on the seat 10. This is done byactivating the valve which controls the flow of air to and from thebellows. The bellows 40 and the scissor-type system 22 then functiontogether with dampening pistons (not shown) as a suspension system ofthe seat, and in normal movement of the seat 10 in a vertical directionthe belt 54 is rolled out of or into the belt reel 52 respectively.However, should a situation arise in which the vehicle is exposed to aviolent change of speed, for example powerful braking or collision, theseat 10 will be exposed to powerful acceleration upwards. The belt reel52 will then lock the belt 54 and thereby prevent the seat from movingupwards relative to the frame 20. This is important, as otherwise theseat's suspension system amplifies the acceleration of the seat andthereby of the person sitting in the seat.

In certain driving situations, the seat suspension can lead to impairedinstead of improved driving comfort for the driver. Since a vehicle suchas a modern lorry is provided on the one hand with wheel suspension andsuspension of the lorry cab on the other and in addition with seatsuspension, this can lead in certain types of road states to thesuspension system getting out of phase, i.e., instead of dampening anunevenness the seat's suspension amplifies it. In these situations it isdesirable to be able to lock the seat's suspension so that the seat 10remains rigid relative to the frame 20. This is achieved according tothe invention by the driver activating the locking mechanism of the beltreel 52, which prevents the belt 54 from being able to be pulled out.The driver then increases the pressure in the bellows 40 so that thiswill press the seat upwards. Movement is prevented, however, by the belt54, at which the seat is so to speak “locked” in this position andremains rigid. When the driver wishes to regain the suspensionpossibilities of the seat, he reduces the pressure at the same time asthe locking mechanism in the reel is deactivated.

The function of locking the reel and pressurizing the bellows ispreferably integrated into one and the same handle or push-buttonarranged on the seat for ease of handling.

It is of course also conceivable for locking of the seat to take placeby means of some mechanical device, which locks the position between thescissor-type arms, for example, or some additional articulatedarrangement which can fix the seat 10 in height.

However, it is an advantage of the device described above thatcomponents which are already attached and which are used for otherfunctions, such as the bellows and the belt/belt reel, can also beutilised to obtain a further function, namely fixing of the seat at anoptional height.

It should be understood that the invention is not restricted to theembodiment described above and shown in the drawings, but can bemodified within the scope of the following patent claims.

What is claimed is:
 1. A vehicle seat which can normally move between alower end position and an upper end position and first means capable ofcushioning/dampening movements of the seat in a vertical direction,characterized in that the vehicle seat also comprises second meanscapable of locking the cushioning/dampening movements of the first meansat an optional height position of the seat between said end positions;wherein said second means for locking the movement of the vehicle seaton acceleration comprises a belt reel and a belt rolled up on the beltreel, and a locking device capable of locking the belt reel when thebelt is unrolled in an accelerated manner; and wherein the lockingdevice of the belt reel can be brought to lock the rotation of the beltreel in an optionally desired position, and the position of the seat canbe locked in an optional position by locking the rotation of the beltreel and pressurizing bellows so that the bellows is pressed upwards andtensions the belt.
 2. The vehicle seat according to claim 1,characterized in that said second means is capable of locking themovement of the seat upwards when the seat is exposed to acceleration inthe upwards direction.
 3. The vehicle seat according to claim 2, whereinthe belt reel and the belt are affixed between the seat and a seatattachment.
 4. The vehicle seat according to claim 1, characterized inthat said first means capable of cushioning/dampening the seat comprisean air bellows arranged between the seat and a seat attachment arrangedto a floor of a vehicle.
 5. The vehicle seat according to claim 1,characterized in that said first means are arranged in the vehicleseat's front section, while said second means are arranged in thevehicle seat's rear section.
 6. The vehicle seat according to claim 5,characerized in that the centers of the first and second means coincidewith the longitudinal center line of the vehicle seat.